Try to avoid unnecessary CC table dups

Author: jhawthorn

vm_insnhelper.c

@@ -2130,17 +2130,14 @@ vm_populate_cc(VALUE klass, const struct rb_callinfo * const ci, ID mid)
                 VALUE attach = RCLASS_ATTACHED_OBJECT(klass);
                 rcu_cc_tbl_p = RB_TYPE_P(attach, T_CLASS) || RB_TYPE_P(attach, T_MODULE);
             }
-            if (rcu_cc_tbl_p) {
-                cc_tbl = rb_vm_cc_table_dup(cc_tbl, klass);
-            }
         }
     }
 
     RB_DEBUG_COUNTER_INC(cc_not_found_in_ccs);
 
     const rb_callable_method_entry_t *cme;
 
-    cme = rb_callable_method_entry(klass, mid, cc_tbl == original_cc_table);
+    cme = rb_callable_method_entry(klass, mid, !rcu_cc_tbl_p && cc_tbl == original_cc_table);
 
     VM_ASSERT(cme == NULL || IMEMO_TYPE_P(cme, imemo_ment));
 
@@ -2150,6 +2147,10 @@ vm_populate_cc(VALUE klass, const struct rb_callinfo * const ci, ID mid)
         return &vm_empty_cc;
     }
 
+    if (rcu_cc_tbl_p) {
+        cc_tbl = rb_vm_cc_table_dup(cc_tbl, klass);
+    }
+
     VM_ASSERT(cme == rb_callable_method_entry(klass, mid, false));
 
     METHOD_ENTRY_CACHED_SET((struct rb_callable_method_entry_struct *)cme);